Dear theresaaa,
So sorry to hear about your son. I hope he gets well soon or at least have it unmanagement so he can lead a normal life. Cases are all different from patient to patient so I could only share with you my experience with my son.
He was 3.5 years old when he first showed signs of HSP (of course we didn't know what it was then) and he was admitted in Jan 2016. After 10 days in hospital the Dr. was not able to confirm his case but only suspects its HSP. During the whole time he didn't have appitite and was on drips. Eventually we sent him to Singapore NUH and it was diagnosed as HSP after doing a scope to rule out other possiblities. In his case, it started with stomach ache and for the first 10 days, he has no signs on rash or swollen joints. Each time he eats, the pain becomes worse leading to vomitting and eventually he rather starve which is why he is on drips.
Its been a year now and he is still classified by the Singapore Dr. who is treating him as chronic. Over the course of 2016, he had many relapses which largely depends on managing it via steroids. Initially we were told that it is self limiting and will eventually go away. After being on steriods for 6 months, the Dr. replaced it with Cellcept and he had to learn to swallow pills with he takes 4 pills daily. This course has allowed him to recover from the side effects of steriods but that does not mean he is all well. As symptoms of all patients are different, we as parents learned that we are the best person to know if a replapse is happening as we spend mote time with our son and can best observe his behavious leading to a relapse. Early 2017, we did a follow-up and was told to continue the midication and observer for another 3 months. IF he does not have any episods, then MAYBE we can start reducing the dosage. Steroids are on stand-by only in an event soe infection causes a relapse.
To answer your question, no one knows when it will go away. We can pray and hope for the best. Being able to diagnose it its the best and from now on is learning how to "manage" his relapse. I've searched the net and believe you have so too only to find that there is no clear anwer. So what is important now? My opinion is "manage it". You will learn and eventually be the best person to detect a relapse as you can see all the change in mood, behavious and visible signs such as redness, rash spots and evenutally swealling. Managing it means to intercept its degree of pain before it ruins his day(s). If you step-in early upon confident diagnostic, you can provide him with suitable dosage of medication to keep it at bay and he'll well and leading a normal life again. However this does not mean over reacting too early and misdiagnose the symptom.
For example, my son's HSP has always starts with stomach pain. We do not give him meds because he complains but rather we give it some time to rule out possiblities such as normal stomach pain of indigession, constipation or just gas. First we try to help him relief the pain by rubbing on his tummy, drinking more water or making him sit on the potty. We will monitor for 3 days. If its consistant and he becomes inactive, poor appitite, not willing to walk, can't stand straight or so, then we can be quite sure its a relapse.
Thank God for giving us hope, friends who gives us courage and portals like this where we know that we are not alone. So we stop asking when will it go away but rather how can we make his life better. Fingerscrossed, maybe we can eventually reduce the Cellcept he is taking eventually. By the way, Cellcept is a drug made for transplant patient so it has similiar effects by lowering the immunesystem so that it stops attacking the body. Please consult your Dr. for proper medication. I'm just sharing our experiences with time and medication taken to encourage you to focus on managing.
I hope you feel must better to know that with today's medicine, your son can have happy days ahead and within reach. Hopefully in future the doctors can eventually find the cause and discover a one-off solution. In the mean time, learn to manage it and with it under control, they can be jumping and running and happy again.
Take care and have faith.